Scientists Discover the Genomic Origins of Canola

Sept. 3, 2014

Dr. J. Chris Pires is an associate professor of biological sciences

Brassica plants have been bred for centuries and result in produce and products diverse enough to show up in supermarkets all over the world. Brassica napus, more commonly known as rapeseed or canola, can be used to make one of the most common vegetable oils. Until now, very little has been known about the origin of this kitchen staple.

Pires says, “In this study, we demonstrate that naturally occurring chromosomal rearrangements, called homoeologous exchanges, are the genetic bases for traits that were then selected by humans as part of the process of domestication and crop improvement.”

Many domesticated plants arose through the meeting of multiple genomes through hybridization and genome doubling, known as polyploidy. Brassica napus is no exception; it has a complex genome because it was formed thousands of years ago during the Neolithic Era when two plant species, Brassica rapa (turnips and cabbage) and Brassica oleracea (broccoli, cauliflower, collard greens, kale), combined in the wild.

Pires interpreted the impact of chromosomal rearrangements on phenotype. “In previous studies, we have shown that chromosomal rearrangements have played a significant role in the evolution of agronomic traits like flowering time and plant height,” he says. “This paper showed that these large-scale genetic exchanges are prevalent in crop plants and underlie numerous traits, such as mustard oil chemistry.”

The findings of the study will help scientists understand how plant genomes evolve in the context of domestication. But that’s not all. “This study shows that in addition to variation in genetic sequence, there is also variation in the copy numbers of genes,” says Pires. “This copy number variation—CNV—is becoming an increasingly important phenomenon to study to make advances in both medical research and crop improvement.”